The present invention relates to a drive control device for controlling a direct current motor that drives a movable body provided in a game machine.
A game machine, such as a reel game machine or a pinball game machine, has been devised for executing a performance that appeals to the player's sense of vision, sense of hearing or feeling so as to enhance the player's interest. Especially, in order to execute a performance that appeals to the player's sense of vision, a movable body, such as a movable accessory, may be provided in the game machine. A movement range and a moving speed of the movable body have previously been set in accordance with the performance. Hence, in general, a rotation amount per step has been fixed and the movable body is driven by a stepping motor capable of controlling a rotation amount in units of steps. Then, a processor unit for performance (hereinafter simply referred to as performance CPU) as one example of an upper-level control device transmits, to a control circuit of the stepping motor, a command to rotate the stepping motor just the number of steps corresponding to a movement amount of the movable body that moves to a designated position in accordance with a state of a game. Hence the stepping motor is rotated just that number of steps, resulting in that the movable body moves to the designated position (e.g., Unexamined Japanese Patent Publication No. 2009-247833). Further, in order to accurately control an operation of the movable accessory, the following technique has been proposed: step-out of the motor is detected based on the number of steps given to the motor and a position of the movable accessory detected by a photo sensor, and a CPU sets a deceleration pattern for the motor in accordance with the degree of the step-out and controls the motor in the deceleration pattern (e.g., Unexamined Japanese Patent Publication No. 2011-67429).
In recent years, there has been a tendency of increase in number of movable bodies installed in a game machine so as to enhance the player's interest. With increase in number of movable bodies installed in the game machine, the number of motors that drive the respective movable bodies also increases. However, since a space of the rear surface of the game machine is limited, the more the number of motors increases, the more difficult it is to arrange those motors in the game machine. In particular, the stepping motor needs to perform excitation control on a plurality of phases, and thus has a complicated structure, making a size of the stepping motor large. Further, a price of the stepping motor is relatively high. Therefore, the increase in number of stepping motors is not preferred.
Moreover, a large-sized movable accessory may be installed in the game machine so as to enhance the player's interest. Driving such a movable accessory requires a motor with high torque. However, increasing the torque of the stepping motor necessitates increasing the size of the stepping motor itself, which might result in making the arrangement space more difficult to ensure.
On the other hand, there are generally available motors such as a direct current motor. A price of the direct current motor is lower than that of the stepping motor, and for exertion of the same torque as that of the stepping motor, the direct current motor may be made be smaller in size than the stepping motor. However, the direct current motor cannot directly designate a rotation amount. Therefore, even when electric power that drives the direct current motor remains unchanged, a rotation amount per unit time, namely a rotational speed, changes depending on a load that is applied to the direct current motor.